This one is the one I built. It has one vent on top as you can see here. One thing I stayed away from was any galvanized piping in the build. I see you have galvanized vents. That may be okay, they are used to take the smoke/heat out of the chamber, but I would just play it safe and try to find yourself some stove pipe. Mine works great with the one vent on top, pretty much centered.
You did put out some great looking grum there. Loaded her up and did an awesome job. Awesome!
yeah I have seen your smoker before used it to help me build mine, and the center vent was something I was really concidering, but I saw more with 2 so I ran with it, and I am going to find some stove pipe soon, just haven't found any 4 inch yet... still lookin, but this will work for now to get the smoker away from the food, I just went cheap with some stakes and chit to avoid having to buy really much of anything for mine, no kits or door for me... If I could have I prolly would have built this thing the true redneck way with some duct tape!!